Aerobic exercise may increase brain size: study

Aerobic exercise can improve memory function and maintain brain health as we age, a new study has found.
Researchers from the Western Sydney University in Australia examined the effects of aerobic exercise on a region of the brain called the hippocampus, which is critical for memory and other brain functions.
Brain health decreases with age, with the average brain shrinking by about five per cent per decade after the age of 40.
The researchers systematically reviewed 14 clinical trials which examined the brain scans of 737 people before and after aerobic exercise programs or in control conditions.
The participants, aged between 24 and 76 years, included a mix of healthy adults, people with mild cognitive impairment such as Alzheimer's and people with a clinical diagnosis of mental illness including depression and schizophrenia.

The researchers examined effects of aerobic exercise, including stationary cycling, walking, and treadmill running. The length of the interventions ranged from three to 24 months with a range of two to five sessions per week.

The results, published in the journal NeuroImage, showed that while exercise had no effect on total hippocampal volume, it did significantly increase the size of the left region of the hippocampus in humans.
"When you exercise you produce a chemical called brain- derived neurotrophic factor (BDNF), which may help to prevent age-related decline by reducing the deterioration of the brain," said Joseph Firth, from the National Institute of Complementary Medicine (NICM) at Western Sydney University.

"Our data showed that, rather than actually increasing the size of the hippocampus per se, the main 'brain benefits' are due to aerobic exercise slowing down the deterioration in brain size," he said.
"In other words, exercise can be seen as a maintenance programme for the brain," he added.